Water resistance ratings in watches – water-resistant, waterproof – what do these terms mean?
Almost every wristwatch is labeled as water-resistant, waterproof, or water-protected. But what do these terms really mean?
A watch’s water resistance is often indicated as atmospheric pressure (ATM) or its equivalent depth in meters. For example, "3 ATM" signifies a theoretical water resistance up to 30 meters in laboratory conditions.
This often causes confusion, as in practice, watches rated 3 ATM are protected only from splashes of water. They should not be used for swimming. Official water resistance ratings don’t account for the motion of the hand or water, both of which increase water pressure on the watch significantly. Thus, a rating of 3 ATM / 30M does not mean the watch can withstand submersion to 30 meters in typical use.
Practically, watches with a minimum of 5 ATM water resistance are splash-proof, 10 ATM watches are suitable for swimming, and 20 ATM watches can handle surface-level diving.
Watches rated 100 M, 10 bar, and 10 ATM all correspond to the same level of water resistance and are essentially equivalent.
Water resistance is not a permanent feature. Over time, gaskets may dry out, harden, and become brittle. Temperature changes also affect gaskets. Even if a watch is water-resistant, it should not be worn in a bathtub or sauna, as moisture may condense inside the watch when exposed to extreme temperature and humidity changes.
Watch Water Resistance Ratings
- No marking, not water-resistant = The watch must be protected from all moisture; it should not get wet.
- 1 ATM = drip-resistant: Tolerates occasional splashes of water.
- 3 ATM = water-protected, splash-proof: The watch is protected from splashes, such as rain, but should not be submerged in water or worn while swimming or in a sauna.
- 5 ATM = limited water resistance: The watch can handle damp conditions, such as surface-level water. It can technically be used for swimming but is not recommended. Showering is allowed.
- 10 ATM = water-resistant: Suitable for surface activities and snorkeling, but not for scuba diving.
- 20 ATM = specialty water-resistant: Suitable for scuba diving. However, it should not be used at depths requiring mixed gases, such as helium.
- 30 ATM = specialty water-resistant: Suitable for deep diving and professional diving applications.
